Method of resin insert molding a metal member, and a connector block for injectors of an internal combustion engine

Abstract: A method of resin insert molding a metal member, and a connector block (1) for injectors of an internal combustion engine having a bar-like body in which bar-like bus bars (2) are arranged in a parallel attitude and embedded in a resin. In the molding method, a core member (7) includes bus bar slots (9) in which the bus bars are placed in a desired attitude; positioning projections (11) that butt against the inner wall of a mold cavity (16) of a mold for resin molding; and holding-pin holes (12) into which holding pins (17) of the mold cavity are fitted so as to form a separation layer between the bus bars (2) and the holding pins. The assembled core member is inserted into the mold cavity (16) of the mold for resin molding, to be held thereby, and the core member (7) is embedded in a resin to form a desired shape. The injector connector block (1) is formed into a bar-like shape using the molding method.

Description: The invention relates to a method of resin insert molding a metal member, such as an electrical component for an automobile. The invention also relates to a connector block for injectors of an internal combustion engine, in which a metal member such as an electric conductor is embedded in a resin. The connector block can be produced by the resin insert molding method. Molded products made of multiple materials, which may include, for example, metal members inserted into a resin, are injection molded using a process in which the metal members are held in a desired attitude in a mold cavity of a mold for resin molding. Each metal member inserted into the mold cavity is fixed by holding pins protruding into the mold cavity, which leaves holding holes that communicate with the metal member after the mold is removed. Even if the holes are filled after the resin molding process, the post-filled portions are not sufficiently waterproof and airtight. As a result, this technique may cause corrosion of the metal member. In addition, when the metal member is used as an electric conductor, electric failure may occur. A molding method for eliminating these disadvantages has been proposed in e.g. EP-A-0 500 219. In this proposed method, a bus bar bundle, which has bus bars arranged in a desired manner, is partially embedded and held, and a preformed portion having leftover holding pin holes is primarily formed by resin molding. The bus bar bundle with the preformed portion is then inserted into a mold cavity of a mold for resin molding, and the inserted attitude is fixed by fitting holding pins of the mold into the holding pin holes of the preformed portion. Secondary processing is conducted so that the bus bar bundle with the preformed portion is embedded in a resin to form a desired form. Japanese Utility Model Publication (Kokai) No. HEI 3-77062, and Japanese Patent Publication (Kokai) No. HEI 4-263913 disclose connector blocks for injectors of an internal combustion engine in which connecting ends are formed by vertically bending bus bars to form tip ends that rise from the bus bar main portions and function as tab terminals. Each of the bus bars, except the tab terminals, is embedded in a resin so that the tab terminals are formed as an injector connecting portion protruding from the main portion. Although the molding methods described above have the advantages that the bus bars embedded in the resin are prevented from being corroded and electrically short-circuited, one method requires complex bus bar shapes and a plurality of steps to resin-mold the insert, and the other method requires primary molding for providing the preformed portion and secondary molding for producing the desired final resin molding product. Therefore, the operation is cumbersome so that the molding productivity is poor and molding costs are high. A prior art connector block for injectors of an internal combustion engine also has several drawbacks. For example, the shape of the bus bars for forming the injector connecting portion is complex and hence requires a great deal of manufacturing time, which increases the cost. The configuration in which the injector connection portion protrudes from the main portion (having a bar-like shape) increases the size of the connector block. From a qualitative viewpoint of preventing the bus bar from being corroded and electrically short-circuiting, the prior art methods require resin-molding with primary and secondary molding steps, thereby inevitably further increasing the costs. It is thus an object of the invention to provide a molding method and a connector block for injectors of an internal combustion engine, respectively, that can eliminate the above-discussed disadvantages. In a first aspect of the present invention, there is provided a method for insert molding a connector, said connector having metal members embedded in a resin, said metal members being inserted into a mold cavity of a mold for resin molding, said mold having holding pins protruding therefrom, said method comprising the steps of: (a) arranging said metal members in a molding position, thereby forming a molding assembly; (b) inserting said molding assembly into said mold cavity while fitting front half portions of said holding pins into holding pin holes provided at said molding assembly, said holding pin holes being positioned to create a separation layer between surfaces of said holding pin holes and said metal members, said molding assembly furthermore having positioning projections butting against an inner wall of said mold cavity; and (c) injecting said resin into said mold cavity. According to the first aspect of the present invention, (d) said step (c) of arranging said metal members in a molding position is accomplished by inserting the metal members within slots of a core, said metal members and said core forming said molding assembly to be inserted into said mold cavity; and (e) in said step (b) of inserting said molding assembly into said mold cavity, said front half portions of said holding pins are inserted into said holding pin holes provided at said core, said holding pin holes being positioned to create said separation layer between surfaces of said holding pin holes and said metal members, said core furthermore having said positioning projections butting against an inner wall of said mold cavity. According to a second aspect of the present invention there is provided a connector block for injectors of an internal combustion engine, comprising: a bar-like body having a core embedded in a resin, said core accommodating bus bars each having a band-like shape, said bus bars being arranged parallel to one another; a wire harness connecting portion formed at one end of said bar-like body, said bus bars having tip ends exposed in said connecting portion; and injector connecting portions for connecting said bus bars through junction terminals to injectors of an internal combustion engine, said injector connecting portions being formed at a plurality of positions on said bar-like body, wherein according to the present invention said core having a plurality of slots for accomodating said band-like metal bus bars disposed in respective ones of said slots, thereby forming a molding assembly for insertion into a mold. In the molding method of the invention, the bus bars are set in the core member, and the core member is inserted into and held in the mold cavity of the mold and embedded in a resin. Therefore, resin injection molding can be accomplished by a single step so that the molding process is simplified and molding productivity is improved. In a resin insert molding product of the metal member that is formed by the method, the separation layer formed by the core member is created or formed between the holding pin holes and the metal member. Therefore, contact between the metal member and ingress of air or water is completely prevented from occurring, thereby sufficiently ensuring waterproof and airtight connectors. The connector block for injectors of an internal combustion engine, which is configured as described above, is formed by the molding method, and hence can attain the above-mentioned functions. The connector block has a structure in which the bus bars have a simple bar-like shape and are arranged in parallel with their faces opposed to each other. Intermediate and end portions of the bus bars are formed as the injector connecting portions that connect through the junction terminals to the injectors of the internal combustion engine. Moreover, the bus bars have a simple structure, thereby promoting the simplification in structure and the miniaturization of the injector connector block. Because the bus bars are simple and thus free from a complex shape, the process of forming the bus bars can be streamlined and simplified. Advantageous modifications of the present invention according to its two aspects are set forth in the respective subclaims. Accordingly, said metal members may have a metal-band shape and said step (a) of arranging said metal members in a molding position comprises placing the metal bands within slots provided on said core to form said molding assembly. In said step (b) of inserting said molding assembly into said mold cavity said positioning protrusions formed on the core may abut against said inner surface of said mold, thereby forming a space between said metal members and said inner surface of said mold, said resin being injected into and filling said space. Said step (a) of arranging may include placing junction terminals as well as said metal members in said core to form said molding assembly. The method may further comprise communicating the metal members, through said junction terminals, with injectors of an internal combustion engine. In a modification of the connector block, said injector connecting portions may have a structure in which said bus bars are exposed in coupling recesses, and said junction terminals are attached to said coupling recesses, said junction terminals having contacting portions for the injectors of the internal combustion engine. Further, the bus bars can be arranged to be not vertically bent along their band edges. The core may includes a main column and a plurality of bus bar receiving portions, said main column connecting said bus bar receiving portions. Spaces adjacent said main column and between said bus bar receiving portions can be provided, which are adapted to align with injector connection portions that communicate said bus bars with injectors of an automotive engine. The core may have a first surface provided with holding pin recesses and a second surface provided with positioning protrusions. These and other aspects and advantages of the present invention are described in or become apparent from the following detailed description of preferred embodiments to be taken in conjunction with the accompanying drawings, in which: Figs. 1(A)-(D) show the molding method and structure of a connector block for injectors of an internal combustion engine of an embodiment of the invention, illustrating the sequential molding procedure; Fig. 2 is a section view taken along line I-I of Fig. 1(C); Fig. 3 is a section view taken along line II-II of Fig. 1(C); Fig. 4 is a cross section view showing a state in which a core member used in the embodiment of Figs. 1(A)-(D) is inserted into a mold cavity; Figs. 5(A)-(D) show section shapes of main portions of the injector connector block of the embodiment of Figs. 1(A)-(D), wherein Fig. 5(A) is a section view of a wire harness connecting portion, and Figs. 5(B) to Fig. 5(D) are section views of injector connecting portions; and Fig. 6 is a section view of an injector connecting portion of an injector connector block according to another embodiment of the invention. A first embodiment of the invention will now be described with reference to Figs. 1(A)-(D) showing the molding procedure, method, and structure of the connector block. A connector block 1 for injectors of an internal combustion engine includes bus bars 2 having metal members formed by a resin insert molding process. Four bus bars 2 (Fig. 1(A)) have a simple band-like shape and straight, unbent band edges arranged in parallel in such a manner that faces of adjacent bands are opposed to each other. Ends on one side of the bus bars 2 protrude to form tab-like terminals 5, thereby constituting a wire harness connecting portion 3. Injector connecting portions 4A, 4B, and 4C (Fig. 1(D)), through which the bus bars 2 in the arranged attitude are partially exposed, are formed at the other ends and intermediate positions of the bus bars 2. Each bus bar 2, except the tab-like terminals 5 and the injector connecting portions 4A, 4B, and 4C, are embedded in a resin, thereby forming the bar-like connector block 1 for injectors of an internal combustion engine. In the formation of the connector block 1, a core member 7 (Fig. 1(B)) for accommodating the bus bars 2 in a predetermined attitude or first position is used. The core member 7 is inserted and held in a mold cavity 16 (Fig. 4) of a mold for resin molding, and a single step of resin injection molding is conducted to form a resin molding product of a desired shape. Specifically, the core member 7 has a structure in which bus bar receiving portions 8A, 8B, and 8C are formed at intervals in the main column portion 10 passing through the longitudinal center of the core member 7. The bus bar receiving portions 8A, 8B, and 8C have bus bar slots 9 for respectively receiving the band-like bus bars 2 in such a manner that the bus bars extend in the longitudinally direction of the core member. The portion between the bus bar receiving portions 8A and 8B, and that between the bus bar receiving portions 8B and 8C, is configured only by the main column portion 10. When the four bus bars 2 are inserted from the top of the bus bar slots 9, the bus bars 2 are held in the desired attitude or position in the resin insert 7. The bus bars 2 in the region of the main column portion 10 are exposed (Fig. 3). The tab-like terminals 5 at the ends of one side of the bus bars 2 protrude from a front end of the bus bar receiving portion 8A. Only two bus bars 2 protrude in a desired length toward the back of the bus bar receiving portion 8C in the rear end, thereby constituting a bar-like body made of the resin. Moreover, with reference to Figs. 2 and 4, the bus bar receiving portions 8A, 8B, and 8C of the core member 7 are provided with positioning projections 11 when the core member 7 is inserted into a mold cavity 16 in a resin molding step (described later). Front half portions of holding pins 17 of the mold protrude into the mold cavity 16 and holding pin holes 12, and are fitted and oriented in such a manner that the bottoms of the holes do not reach the bus bars 2, thereby creating a separation layer 13 so that the bus bars 2 are not exposed. The bus bars 2 are provided with engaging projections 23 for holding the attitude of the inserted bus bars 2, and the bus bar slots 9 are provided with dimples (not shown) for receiving the engaging projections 23. In the case where the dimples are not formed, the bus bars 2 may have dimensions under which the bus bars 2 are forcedly inserted into the bus bar slots 9, thereby holding the attitude of the bus bars 2. The bus bars 2 are accommodated and set in the core member 7. The core member 7 in the accommodated state is inserted into the mold cavity 16 formed by combining upper and lower molds 14 and 15 (see Fig. 4). The positioning projections 11 of the core member 7 butt against the inner wall of the mold cavity 16, and the holding pins 17 protruding from the lower mold 15 are fitted into the holding-pin holes 12 of the core member 7 so that the inserted attitude of the core member is fixed. A resin is injected into the space in the periphery of the core member 7 in the inserted attitude, so that the bus bars 2 are embedded in the resin 6 to form the bar-like injector connector block 1 having a desired shape. Holes 25 formed by the holding pins 17 are post-filled as required. With reference to Fig. 5(A), the injector connector block 1 formed by the injection process described above has a structure in which the wire harness connecting portion 3 is formed by enclosing the tab-like terminals 5 by the resin 6. The portions of the core member 7 in the regions adjacent the main column portion 10 are configured as the injector connecting portions 4A, 4B, and 4C (see Figs. 5(B), 5(C), and 5(D)), wherein intermediate and end portions of the bus bars 2 are exposed in coupling recesses 18 that open downwardly. Junction terminals 20 each have a first end including a bus bar contacting portion 22, and a second end including an injector contacting portion 21. The portions 21 and 22 are respectively formed and attached to respective ones of the exposed bus bars 2 of the injector connecting portions 4A, 4B, and 4C. The injector connector block 1 is pressed down against the top of a group of injectors (not shown) of an internal combustion engine to be attached thereto. The injector connecting portions 4A, 4B, and 4C are coupled with the respective injectors, and connectors of a wire harness are coupled with the wire harness connecting portion 3, thereby electrically connecting the injectors to the wire harness. The molding method of the invention and the injector connector block 1 formed by the molding method perform the above-mentioned function, and the formation can be accomplished by a single resin molding step. Therefore, the molding process can be simplified so that the cost is reduced. Moreover, the injector connector block 1 is free from a bulge portion or a protruding portion, and hence bus bars to be inserted can have a simplified shape, thereby reducing overall size and cost. The injector connector block 1 of the invention is not restricted to the embodiment described above. For example, the injector connecting portions 4 may have a structure in which, as shown in Fig. 6, the junction terminals 20 are previously combined with the bus bars 2. Only injector connecting portions 21, which are lower portions of the junction terminals 20, are exposed in the coupling recesses 18. The bus bars 2, and the upper portions of the junction terminals 20, are embedded in the resin 6. The method of resin insert molding a metal member of the invention can be used not only in the formation of the above-mentioned injector connector block 1 but also in a wide variety of formations wherein plural metal members are arranged in a specified layout and then insert-molded in a resin. As described above, according to the method of resin insert molding a metal member of the invention, plural metal members can be insert-molded in a resin while specifying their arranged attitude by a single step of injection molding using a mold for resin molding. Therefore, the molding process can be simplified so that the moldability is improved and the molding cost is reduced. The connector block for injectors of an internal combustion engine of the invention, which is produced by the molding method, can attain the above-mentioned effects of improved moldability and reduced molding cost. Other advantages and effects are that the bus bars can have a simple shape and hence the overall structure can be simplified and reduced in size, thereby further promoting miniaturization of the connector block and reduction of cost. The invention has been described in detail with reference to preferred embodiments thereof, which are intended to be illustrative and not limiting. Of course, various modifications can be made without departing from the invention.

Claims: A method for insert molding a connector, said connector having metal members (2) embedded in a resin, said metal members (2) being inserted into a mold cavity (16) of a mold for resin molding, said mold having holding pins (17) protruding therefrom, said method comprising the steps of: (a) arranging said metal members (2) in a molding position, thereby forming a molding assembly; (b) inserting said molding assembly into said mold cavity (16) while fitting front half portions of said holding pins (17) into holding pin holes (12) provided at said molding assembly, said holding pin holes (12) being positioned to create a separation layer (13) between surfaces of said holding pin holes (12) and said metal members (2), said molding assembly furthermore having positioning projections (11) butting against an inner wall of said mold cavity (16); and (c) injecting said resin into said mold cavity (16), characterized in that (d) said step (c) of arranging said metal members (2) in a molding position is accomplished by inserting the metal members (2) within slots (9) of a core (7), said metal members (2) and said core (7) forming said molding assembly to be inserted into said mold cavity (16); and (e) in said step (b) of inserting said molding assembly into said mold cavity (16), said front half portions of said holding pins (17) are inserted into said holding pin holes (12) provided at said core (7), said holding pin holes (12) being positioned to create said separation layer (13) between surfaces of said holding pin holes (12) and said metal members (2), said core (7) furthermore having said positioning projections (11) butting against an inner wall of said mold cavity (16). The method of claim 1, wherein said metal members (2) have a metal-band shape and said step (a) of arranging said metal members (2) in a molding position comprises placing the metal bands within slots (9) provided on said core (7) to form said molding assembly. The method of claim 1 or 2, wherein in said step (b) of inserting said molding assembly into said mold cavity (16) said positioning protrusions (11) formed on the core (7) abut against said inner surface of said mold, thereby forming a space between said metal members (2) and said inner surface of said mold, said resin being injected into and filling said space. The method of anyone of claims 1 to 3, wherein said step (a) of arranging includes placing junction terminals (20) as well as said metal members (2) in said core (7) to form said molding assembly. The method of claim 4, further comprising communicating the metal members (2), through said junction terminals (20), with injectors of an internal combustion engine. A connector block for injectors of an internal combustion engine, comprising: a bar-like body having a core (7) embedded in a resin, said core (7) accommodating bus bars (2) each having a band-like shape, said bus bars (2) being arranged parallel to one another; a wire harness connecting portion (3) formed at one end of said bar-like body, said bus bars (2) having tip ends (5) exposed in said connecting portion; and injector connecting portions (4) for connecting said bus bars (2) through junction terminals (20) to injectors of an internal combustion engine, said injector connecting portions (4) being formed at a plurality of positions on said bar-like body, characterized in that said core (7) having a plurality of slots (9) for accomodating said band-like metal bus bars (2) disposed in respective ones of said slots (9), thereby forming a molding assembly for insertion into a mold. The connector block of claim 6, wherein said injector connecting portions (4) have a structure in which said bus bars (2) are exposed in coupling recesses, and said junction terminals (20) are attached to said coupling recesses, said junction terminals (20) having contacting portions (21) for the injectors of the internal combustion engine. The connector block of claim 6 or 7, wherein the bus bars (2) are not vertically bent along their band edges. The connector block of anyone of claims 6 to 8, wherein the core (7) includes a main column (10) and a plurality of bus bar receiving portions (8), said main column connecting said bus bar receiving portions. The connector block of claim 9, wherein spaces adjacent said main column (10) and between said bus bar receiving portions (8) are adapted to align with injector connection portions (4) that communicate said bus bars (2) with injectors of an automotive engine. The connector block of anyone of claims 6 to 10, wherein the core (7) has a first surface provided with holding pin recesses (12) and a second surface provided with positioning protrusions (11).

Inventors: FUJITANI MITSUHIRO, KONOYA HISASHI, FUJITANI, MITSUHIRO, KONOYA, HISASHI, Fujitani, Mitsuhiro, c/o Sumitomo Wiring Systems,, Konoya, Hisashi, c/o Sumitomo Wiring Systems, Ltd
Applicants: SUMITOMO WIRING SYSTEMS, SUMITOMO WIRING SYSTEMS, LTD.
Application year: 1994
Main classification: B29C33
IPC codes: B29C33, F02M51, B29L31, B29C45, B29K105, B29C70